Fluid-controlled memory with nondestructive read out



May 24, 1966 J. H. MEIER 3,252,481

FLUID-CONTROLLED MEMORY WITH NON-DESTRUCTIVE READ OUT Filed Aug. 29, 1963 2 Sheets-Sheet l IIVVE/VTOR JOHANN H. MEIE A TTOR/VE) United States Patent FLUID-CONTROLLED MEMORY WITH NON DESTRUCTIVE READ OUT Johann H. Meier, Vestal, N.Y., assignor to International Business Machines Corporation, New York, N.Y., a .corporation of New York Filed Aug. 29, 1963, Ser. No. 305,401 7 Claims. (Cl. 137--625.4)

This invention relates to fluid-controlled devices, and more particularly to a fluid-controlled memory of the non-destructive read out type.

In recent years, there has been increasing interest in fluid amplifier-type devices, so named because a low energy fluid input signal can switch a 'hight energy fluid power stream to provide an amplified fluid output signal. It has heretofore been proposed to provide a fluid memory embodying pure fluid amplifiers having no moving parts. In such devices, the fluid power stream is locked on alternatively to one or the other of two outlets; and switching of the stream from one outlet to the other is accomplished by enlarging the separation bubble in a boundary layer control region along the outlet from which the stream is to be switched. However, with memories of this type, if the fluid supply fails, even momentarily, the information stored in the memory will be destroyed. Also, pure fluid memories of this type dissipate considerable fluid energy because they employ a fluid power stream that discharges continuously into one or the other of the outlets.

I There is therefore a need for a device which can be employed as a non-destructive .type of fluid-controlled memory suitable for use with fluid amplifiers in a fluid computer. There is also a need for a fluid-controlled memory which requires fluid energy only during sensing or during switching from one bistable state to the other state.

Accordingly, it is one object of this invention to provide a non-destructive read-out type of fluid-controlled memory wherein the stored information willnot be lost in event offailure of supply from a fluid pressure source.

Another object is to provide an inexpensive and reliable fluid-controlled memory which requires a minimum of fluid power for writing and reading operations (i.e., for setting of its state'and read out of stored information).

Still another object is to provide a fluid-controlled memory that can be set in either of two stable states and reread repeatedly until a SET signal is given to change its state. A further object is to provide a fluid-controlled memory of the above type wherein writing or switching from one state to another is effected by fluid pressure SET signals and reading is effected by fluid pressure SENSE signals.

According to the invention, the fluid-controlled memory comprises an elastic member with external or internal constraints so as to be buckled into one or the other of two bistable states. These states are defined by contact with one or the other of two concavely curved in the corresponding output line. However, if the memher is in its other stable state, in which it uncovers the sense port to the atmospheric chamber, then no output signal will be developed in the output line.

According to another embodiment of the invention,

ice

the chamber is connected to a single sense input line (rather than an atmospheric exhaust port). Depending upon its state, the reed will uncover this input line to one or the other of two sense output lines that open through respective ports formed in the sidewalls of the chamber.

In both embodiments, set ports open through the sidewalls. These are of relatively high flow capacity so that when they are selectively charged, sufficient fluid pressure force will be developed against the elastic member to buckle it inside out to its other stable state. In the second embodiment, sensitive pneumatic diodes or check valves are preferably provided to prevent escape flow of fluid from the sense input line out the uncovered set port, while permitting flow in the reverse direction from a source of switching pressure fluid to the set port. No

such check valves are necessary with the first embodiment.

The foregoing and other objects, features and advantages ,of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings, wherein: p FIG. 1 is a sectional view of a fluid-controlled memory device constructed according to one embodiment of the invention and shown associated with other schematically denoted elements of a fluid-controlled computer;

FIG. 2 is a section of the memory taken along the line 22 of FIG. 1;

FIG. 3 is a sectional view of a fluid-controlled memory constructed according to another embodiment of the where the elastic member is specifically a buckled reed,

invention which preferably includes pneumatic diodes or check valves sensitive to low pressure differentials; and FIG. 4 is a sectional view of a sensitive pneumatic diode capable of use in the memory of FIG. 3; and

FIG. 5 is a sectional view of a memory with a valve subject to internal (rather than external) constraints,

according to another embodiment of the invention.

DescriptionFIGS. 1 and 2 r The fluid-controlled memory device constructed according-to this embodiment of the invention comprises a valve in the form of a flexible reed 10 disposed in a cavity or chamber 11. This cavity is defined between plane and parallel front and rear walls and by two oppositely facing concave sidewalls 12, 13 that intersect at upper and lower V-like junctions 14, 15. The distance between the apexes of the junctions is less than the length of the reed 10 so that the reed will be held in a state of endwise compression at the junctions. Thus, the reed will be constrained to assume either of two stable states defined by oveilying, substantially sealing contact with a respective sense port 16 or 17 formed in, and substantially midway along the corresponding sidewalls 12, 13.

As illustrated, sense input openings 18, 19 lead to the corresponding ports 16, 17 via respective .restrictions or chokes 20, 21; whereas sense output openings 22, 23 have substantially unrestricted communication with the respective ports 16, 17. Set ports 24, 25 open through the sidewalls 12, 13. The size of these ports is suflicient to permit build-up of a fluid pressure force adequate to-initiate shifting of the reed from one stable state'to the opposite stable state.

In operation, assume that the reed 10 is disposed as shown in FIG. 1; that the cavity 11 is connected to a low pressure source (such as the atmosphere) via an exhaust port 26; and that a fluid pressure sense input signal is supplied via opening 18 through choke 20 to port 16. Under such conditions, the reed 10 will eifectively seal off port 16 from the exhaust port 26, and hence a fluid pressure sense output signal will be produced in sense output opening 22. Thiswill denote that reed 10 was in 3,252,481 Patented May 24-, 1966 i its sealing position, which we shall arbitrarily assume to denote a binary 1 condition.

To set the reed 10 to a binary condition, pressure fluid is supplied to set port 24 via a set opening 27. When sufficient fluid pressure force is built up against the side of reed 10, it will start to buckle and temporarily assume higher buckling modes, of which the second mode (denoted by broken lines) is most important. Thereupon the reed will continue to move with a snap-action efiect to its opposite stable state, in which it overlies and substantially seals off port 17 from exhaust port 26, while uncovering port 16 to said exhaust port. If a fluid pressure sense input signal is now applied to opening 18, no fluid output signal will be noted in output opening 22. This is because port 22 now has unrestricted communication with the exhaust port 26 via the uncovered port 16, and hence all of the pressure fluid of the sense input signal will be dissipated to atmosphere via port 26.

In similar manner, a fluidpressure sense output signal will be produced in opening 23 only if the reed seals off port 17. from exhaust port 26 during supply of a fluid pressure sense input signal to opening 19. Resetting of the reed to the position in which it is shown in FIG. 1 is accomplished by supplying a fluid pressure set pulse to a set opening 28.

It is to be noted that, in order to favor the second mode of reed buckling, the set ports 24, 25 are preferably located at a point along the sidewalls 12, 13 about onefourth the distance from the junction (or 14). It is in this area where the amplitude of the second buckling mode is at its maximum; and the least force is therefore required tov produce the second mode, for thereby facilitating snapping of the reed to its opposite stable state. Conversely, the sense ports 16, 17 are located midway 7 along the sidewalls 12, 13. There the amplitude of the second buckling mode is small, and hence the second mode will not be excited by sense signals. Actually, force applied at this point will tend to distend' the reed into the third buckling mode; but since the reed offers considerably more resistance to the third mode than to the second mode, switching of the reed through its third buckling mode takes substantially more pressure and hence is not likely to occur.

It should be noted that the exhaust port 26 is large to promptly vent the pressure fluid supplied via the set opening 27 (or 28) as soon as the reed 10' moves beyond its second mode position and uncovers port 24 (or The large exhaust port 26 also prevents a fluid pressure sense signal from effecting a build-up in pressure in chamber 11.

It will be understood that the pressure fluid sense and set signals may be supplied to the sense input openings 18, 19 and to the set openings 27, 28 from any suitable sources. For example, they may be supplied by solenoids or other electrical-to-pneumatic transducers. Or, as illustrated schematically, they may be amplified fluid pressure signals supplied by improved pure fluid amplifiers such as 30, 31 which are of the type fully shown and described in the copending application of R. R. Schaifer, U.S. Serial No. 283,875, filed May 28, 1963 and assigned to the assignee of the present invention.

Each such fluid amplifier 30, 31 comprises, briefly, an elongated inlet 32 through which. pressure fluid is supso long as a sense output signal is delivered via opening 22 to a control port 42.

plied from a source to provide a fluid power stream that It will be understood that similar amplifiers (notshown) are associated with the openings 19, 28, and 23. Also one set of amplifiers, like 30, 31, 40, can be disposed between and provide amplified sense input and output signals and set signals for two adjacent memory devices.

It will also be noted that fabrication of memories of the type just described is relatively simple and inexpensive. The cavity, ports, lines, chokes and power fluid amplifiers (if used) may be formed by photoetching in the manner already widely known in the art. The reed 10 can readily be inserted into chamber 11, without fastening or adjustment.

As shown in FIGS. 1' and 2, the reed 10 is relatively wide and yet very thin to provide a large surface to mass ratio. Hence, it can readily be accelerated by the pneumatic pressures employed in pure fluid amplifiers and logic systems. The reed is disposed with a minimum of clearance between the front and rear walls 45, 46 of the chamber 11 so as to minimize leakage around the longi tudinal edges of the reed as it is being shifted from one state to the other by a fluid pressure set signal.

Descrip'ti0n-FI G. 3

The fluid-controlled memory constructed according to this embodiment of the invention differs from that shown in FIGS. 1 and 2 in that fluid pressure sense input signals are supplied via a single port 50 to the reed-containing cavity or chamber 51. Upon supply of a sense input signal to port 50, a fluid pressure sense output signal will be delivered through sense outlet port 52 or 53,

according to which of these ports is uncovered to port 50 by .the reed 10. To switch the reed 10 from one state to the other, a fluid pressure set signal is supplied via set opening 54 or 55, as the case may be. Pneumatic diodes or check valves 56, 57 are preferably interposed between the set openings 54, 55 respectively. Thus, check valve 57, for example, prevents a fluid pressure sense input signal from being dissipated by discharge into set opening 55 when said opening is uncovered to the chamber 51 as shown.

In other respects, the structure and operation of this embodiment are similar to that shown and described in connection with FIGS. 1 and 2. It may be noted, however, that the sense outlet ports 52, 53' may be located anywhere along the sidewalls of the chamber 51, because fluid pressure will never build up behind these ports and exert a force against the reed.

Descripti0n-F I G. 4

The pneumatic diode shown in this figure may, if desired, be substituted for the conventional type of check valve 56 or 57 illustrated in FIG. 3.

This diode comprises a flexible reed 61 disposed in a cavity or chamber 62 so configured that the reed is stable when in contact with one sidewall 63 but unstable when moved toward or to the other sidewall 64. Thus, upon supply of pressure fluid to port 65 (which would: beconnected to set opening 54 of FIG. 3), the, reed will be forced laterally and uncover port 65 to an outlet port 66 (leading to the reed 10 in. FIG. 3). However, when the signal to. port 65v dies, the reed: 61 will return to its stable position inv which it is. shown. in FIG. 4. Thus, any back pressure in. port 66 and chamber 62 will: force the reed" 61 even tighter against the mouth of port 65 for preventing. backflow leakage into port 65. To assure the instability of the reed" so that it will always return to its shown pos -t',nitisioi cmf E'IAOI'N shown: position, it is essential that the distance x be less than the distance y, and? that all half-sine curves forming the cavity 62 have equalor substantially equal slope at their endpoints.

Description-FIGURE 5 The fluid-controlled memory constructed according to this embodiment differs from that shown in FIGS. 1 and 2 primarily in that the valve is in the form of a flexible prestressed circular diaphragm 70 held under internal (rather than external) constraint.

This diaphragm is clamped between two housing portions 71, 72 having facing concavities that cooperate to provide a chamber 73. The concavities are symmetrical and dish-shaped and substantially conform to the configuration of the movable part of the diaphragm when it is in either of two stable positions defined by contact with the surfaces 74, 75 of the respective concavities.

The diaphragm 70 is thin enough so that it will develop only very low bending stresses as it is snapped inside out from one of its stable positions to the other. The stifiness of the diaphragm is derived principally from radail and tangential stresses.

When diaphragm 70 is disposed in the stable position in which it is shown in FIG. 5, it eifectively seals off a sense port 76 from chamber 73. Hence, when a superatmospheric or positive fluid pressure sense input signal is supplied via an opening 77 and through 'a restriction 78 to port 76, a positive fluid pressure sense output signal will be produced in a sense output opening 79 to denote a binary 1 state.-

To reset the diaphragm 70 to its binary 0 state, pressure fluid is suplied via opening 80 to a set port 81. When sufficient fluid pressure force is built up against diaphragm 70, it will buckle in a higher mode than denoted by its original pre-stressed state and move with a snap action effect to its opposite stable state, in which it overlies and substantially seals off a sense port 82 from chamber 73, while uncovering port 76 to said chamber.

If a positive fluid pressure sense input signal is now supplied to opening77, a negative output signal will be noted in output opening 79 because the pressure fluid will flow to the atmosphere via an exhaust port 83 and create a suction in opening 79 that will be created by venturi effect since opening 79 is laterally connected to the restriction 78. On the other hand, a positive fluid pressure sense output signal will be produced in an output opening 84 only if diaphragm 70 seals oif port 82 from cavity 73 during a fluid pressure sense input signal applied via a restriction or choke 85 from an input opening 86. To reset the diaphragm to its shown position, a fluid pressure set pulse is supplied via a set opening 87 to a set port 88. After reset of the diaphragm, chamber 73 will be uncovered to atmosphere via an exhaust port 89.

In the embodiments shown in FIGS. 1 and 5, the sense output openings 22, 23 and 84 were located downstream of the restrictions 21, 22 and 85, respectively. Hence no appreciable suction was produced in the particular sense output opening (e.g.,'22) when pressure fluid was discharged via the corresponding sense port 16 to the valve chamber 11 under the binary 0 condition. However, as above noted, such suction can be created in the sense output openings by the venturi effect obtained by connecting such openings (e.g., 79) to the corresponding restriction (rather than downstream of the restriction). Similar pressure sense input signal, according to whether thememory element 10 is in a binary 0 or 1 state. Such an arrangement is especially desirable when using fluid amplifier elements of the so-called Diamond Ordnance Fuze Laboratoriesv (DOFL) bistable turbulent attachment type.

While the invention has been particularly shown and described with reference to preferred embodiments thereof,

it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. A device comprising means providing a chamber, a concavely curved wall in part defining said chamber, and a port formed in said wall,

a valve including an elastic member under constraint at opposite edge portions disposed in said chamber and having one position in which it is flexed convexly to overlie the port and seal off the port fromthe chamber, and displaceable to another position in which it is flexed concavely, by a fluid pressure acting directly thereon and exceeding a predetermined value, and in which position it uncovers the port to the chamber, and

means providing a sense input line and a sense output line having fluid communication with said port, the input line being adapted to convey a fluid pressure signal to the port and the flow capacity of said output line being at least equal to that of the input line to prevent such signal from developing a fluid pressure exceeding said value and suflicient to displace said valve from its said one position to its said other position, so as to cause an output pressure signal to be received in said output line only if said valve is in said one position.

2. A device according to claim 1, including means providing a set line opening through said wall for conveying a pressure fluid set pulse at a pressure exceeding said predetermined value to the convex side of said valve to develop a force thereagainst suflicient to shift said valve from said one position to said other position.

3. A memory device comprising means providing a chamber open to atmosphere and defined by spaced plane and parallel front and rear walls joined to two oppositely arranged concave surfaces that intersect at two spaced junctions, and a sense port opening through each such surface,

a valve including a flexible reed disposed in said chamber and held in a state of endwise compression by contact with said junctions and flexible inside out in one direction or the opposite direction so as to assume one or the other of two bistable positions in which it overlies and selectively seals off from atmosphere one or the other of said ports, and

means providing two pairs of sense input lines and sense output lines, those of each pair having fluid communication with a corresponding one of said ports, each input line being adapted to convey a fluid pressure sense signal to the corresponding sense port and the flow capacity of each sense output line being at least equal to that of the corresponding input line to prevent a sense signal from developing suflicient fluid pressure force to displace said valve from its existing position,

whereby an output signal will be received in a particular one of the output lines only if the valve is positioned to seal 01f the corresponding sense port from atmosphere.

4. A device according to claim 3, including means providing respective set ports each opening through a corresponding one of said concave surfaces and each of larger flow capacity than the corresponding sense input line for conveying a pressure fluid set pulse to exert a fluid pressure force laterally on the valve, whereby supply of a fluid pressure set signal to the set port then covered by the valve will cause the valve to buckle and snap to its other position and into sealing contact with the opposite sense port.

5. In a fluid-controlled device,

means providing a chamber defined in part by a concavely curved wall having a set port and a sense port opening therethrough and another wall facing the first-mentioned wall,

a flexible valve member disposed in said chamber under external constraint by endwise compression and having a stable position in which it is flexed convexly to overlie the ports and seal off the ports from the chamber and movable to another position in which it is flexed at least partially inside out to uncover the ports to the chamber,

means for supplying a pressure fluid signal to the set port to flex the member from its stable position to its said other position, and

means providing an input line and an output line both communicating with said sense port, but the input line being of lesser flow capacity than the output line to prevent pressure fluid supplied to said input line from displacing said member from said stable position, thereby to cause an output signal to be-detected in said output line only if said member is in said stable position while pressure fluid is being supplied to said input line.

6. A device comprising .means providing a chamber, a concavely curved Wall in part defining said chamber and a port formed in said wall,

valve including a deformable member under constraint at opposite edge portions disposed in said chamber and having one position in which it is flexed convexly to overlie the port and seal off the port from the chamber, and displaceable to another position in which it is flexed concavely, by a fluid pressure acting directly thereon and exceeding a predetermined value, and in which position it uncovers the port to the chamber, and

means providing a sense input line connected via a restriction to said port, and a sense output line laterally connected to said restriction, such that upon supply of a fluid pressure signal to the input line an output pressure will be obtained in the output line if: said valve is in said one position and a suction will be created by venturi eflect in the output line if said valve is in its said other position.

7 A device according to claim 6, including means providing a set line opening through said wall for conveying a pressure fluid set pulse at a pressure exceeding said preselected value to the convex side of said valve. to develop a force thereagainst sufficient to shift said valve from said one position to said other position.

References Cited by the Applicant UNITED STATES PATENTS 2,658,972 11/1953 Brown. 2,688,336 9/1954 Huntington. 2,838,783 6/1958 Allen. 2,991,805 7/1961 Page. 3,094,594 6/1963 Watson.

FOREIGN PATENTS 1 498,350 1/1939 Great Britain.

M. CARY NELSON, Primary Examiner.

A. J. IAFFE, Assistant Examiner. 

1. A DEVICE COMPRISING MEANS PROVIDING A CHAMBER, A CONCAVELY CURVED WALL IN PART DEFINING SAID CHAMBER, AND A PORT FORMED IN SAID WALL, A VALVE INCLUDING AN ELASTIC MEMBER UNDER CONSTRAINT AT OPPOSITE EDGE PORTIONS DISPOSED IN SAID CHAMBER AND HAVING ONE POSITION IN WHICH IT IT FLEXED CONVEXLY TO OVERLIE THE PORT AND SEAL OFF THE PORT FROM THE CHAMBER, AND DISPLACEABLE TO ANOTHER POSITION IN WHICH IT IS FLEXED CONCAVELY, BY A FLUID PRESSURE ACTING DIRECTLY THEREON AND EXCEEDING A PREDETERMINED VALUE, AND IN WHICH POSITION IN UNCOVERS THE PORT TO THE CHAMBER, AND MEANS PROVIDING A SENSE INPUT LINE AND A SENSE OUTPUT LINE HAVING FLUID COMMUNICATION WITH SAID PORT, THE INPUT LINE BEING ADAPTED TO CONVEY A FLUID PRESSURE SIGNAL TO THE PORT AND THE FLOW CAPACITY OF SAID OUTPUT LINE BEING AT LEAST EQUAL TO THAT OF THE INPUT LINE TO PREVENT SUCH SIGNAL FROM DEVELOPING A FLUID PRESSURE EXCEEDING SAID VALUE AND SUFFICIENT TO DISPLACE SAID VALVE FROM ITS SAID ONE POSITION TO ITS SAID OTHER POSITION, SO AS TO CAUSE AN OUTPUT PRESSURE SIGNAL TO BE RECEIVED IN SAID OUTPUT LINE ONLY IF SAID VALVE IS IN SAID ONE POSITION. 